The invention pertains to laser devices, including laser scanning devices and laser desorption spectrometers, as well as other devices.
The use of lasers has become increasingly widespread. Lasers can be used for manufacture of products, material analysis, etc. Chemical imaging is one form of material analysis. Chemical imaging using mass spectrometry has attracted increasing interest because of numerous applications for characterizing materials science samples, biological tissues, individual aerosol particles, minerals, forensic evidence, etc. Chemical imaging is often based on secondary ion mass spectrometry (SIMS) by bombarding a surface with atomic primary beams to yield elemental secondary ions from a surface being analyzed. One disadvantage of such techniques includes surface charging that can lead to redeposition of material. Further, for SIMS, chemical imaging usually uses atomic ion primary beams that provide primarily elemental and not molecular chemical information.
Recently, laser desorption (LD) techniques for mass spectrometry have attracted attention because they produce intact molecular ions, avoid surface charging issues, and allow tuning of laser irradiation (wavelength and fluence) to accommodate various sample types. Careful control of laser fluence prevents excessive sputtering that can contaminate adjacent locations of a sample also intended for analysis.
Traditionally, LD microprobe mass spectrometers use scanning techniques that rely on manipulation of a sample target. Alternative LD techniques may accomplish manipulation by moving optical components. In such cases, spatial resolution (minimum controlled displacement of laser energy on the sample target) has been limited to mechanical resolution (minimum controlled displacement per step) of stepper or servo motors used to move the sample target or optical components. Such techniques often encounter problems with reproducible alignment of laser scans with sample targets. Often, such techniques are not easily amenable to analysis under extreme conditions including confined space, high magnetic fields, operation under vacuum, operation under high pressure, operation under hazardous conditions, etc.
In one aspect of the invention, a laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component. Distance H can be greater than distance J. The laser device can include a laser source manipulation mechanism exhibiting a mechanical resolution of positioning a laser source. The mechanical resolution can be less than a spatial resolution of laser energy at the target position as directed through the optical component. As one example, the target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The laser source can be a virtual source and can be placed in scanning motion by the manipulation mechanism. The laser source can also be linked to a pendulum assisting in alignment of laser energy. Further, spatial resolution can approximately equal the mechanical resolution multiplied by a ratio of distance J to distance H. At least one of distance H and distance J can be altered, modifying the spatial resolution. The manipulation mechanism can include a Peaucellier linkage also assisting in laser energy alignment. At least one desorbed energy detection cell can be provided such that the laser device is comprised by a laser desorption spectrometer. The laser device can instead be comprised by other systems.
In another aspect of the invention, a laser device can include an optical component having a vertical index and a lateral index that intersect at an origin, a laser energy source aimed at the origin, and a laser source manipulation mechanism. The manipulation mechanism can link vertical and lateral laser source motion to the respective vertical and lateral indices and auto align laser aim through the origin during laser source motion. As an example, at least one of the lateral index and vertical index can comprise a line. Lateral laser source motion can be physically linked to the lateral index. Vertical laser source motion can be physically linked to the vertical index. The manipulation mechanism can provide a center of lateral pivot for the laser source approximately coincident with the lateral index and a center of vertical pivot for the laser source approximately coincident with the vertical index.
In a further aspect of the invention, a laser device can include a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component. The laser device can include a laser source manipulation mechanism having a mechanical index. The mechanical index can provide a pivot point for laser source lateral motion and a reference point for laser source vertical motion. Lateral displacement of the laser source can produce a related, predictable lateral displacement of laser energy at the target position as directed through the optical component. Vertical displacement of the mechanical index can produce a related, predictable vertical displacement of laser energy at the target position as directed through the optical component. As an example, the optical component can comprise a lens and the mechanical index can track a curved surface of the lens during vertical motion.
In a still further aspect of the invention, a laser device includes an optical component, a laser energy source separated from the optical component, and a laser source manipulation mechanism comprising a Peaucellier linkage. The manipulation mechanism aims the laser source through the optical component. As an example, the Peaucellier linkage can include a mechanical index, the mechanical index providing a pivot point for laser source lateral motion and a reference point for laser source vertical motion.
In another aspect of the invention, a laser device includes a target position located within an adverse environment, an optical component separated from the target position, a laser energy source located outside the adverse environment, and a laser source manipulation mechanism comprising electro-mechanical parts all of which are located outside the adverse environment. The manipulation mechanism can aim the laser source through the optical component at the target position. As one example, the laser source can be separated from the optical component by at least about 1.3 meters (4 feet). The adverse environment can include at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone.